In a three-dimensional (3D) digital cinema theatrical presentation, the masking on the screen may obstruct or encroach on the region in which a subtitle or caption is to have been displayed, thus necessitating a modification to the subtitle, e.g., its position and/or dimensions on the screen. The same situation can arise in a 3D video display, if a full raster of the content or the original subtitle occupies an area larger than a display area of a monitor. In such situations in 3D, not only must the subtitle or caption be adjusted in size or dimensions and/or relocated in a coordinated fashion for each eye's image, but there must also be an accommodation for the 3D content which the caption will overlay, so that the caption does not interfere with apparent depth of elements within the content, nor be unsuitably displayed far into the foreground with respect to the underlying content. The term “apparent depth” is the depth perception by a viewer relative to the screen, caused by the disparity between the left-eye and right-eye images. A 3D presentation is usually constrained to provide apparent depth because viewers at different locations will perceive a different apparent depth for the same element in the image.
In a 3D presentation, the “overlay” or “compositing” of a caption provides that the caption and the associated image or content are combined so as to present the caption, within the image space, readably to a viewer. This necessarily obscures a portion of the image, with the portion of the image that gets obscured being chosen manually (e.g., by an artist or subtitle technician), or in some cases automatically. The caption may be semitransparent in whole or in part.
In the case of 3D, subtitles are generally provided with a specified disparity (i.e., offset between the right- and left-eye subtitles), often measured in pixels, so that the system responsible for rendering the text can render the text with the 3D image content and have the appropriate offset applied between the right- and left-eye subtitles so that they are correctly placed. When the location offset between the right- and left-eye is zero, the subtitle appears to be at the surface of the screen. When the location places the subtitle for the right eye to the right of the subtitle for the left eye, then the subtitle appears to be behind the screen. If the subtitle for the right eye is to the left of the subtitle for the left eye, then the subtitle appears to be in front of the screen.
Various methods and systems for subtitle display have been described by others in commonly-assigned patent applications, e.g., Redmann in published PCT patent application, WO 2010/096030, entitled “Method and Apparatus for Preparing Subtitles for Display” and Izzat et al. in PCT published patent application, WO2008/115222, entitled “System and Method for Combining Text with Three-Dimensional Content”. The teachings in both PCT publications are herein incorporated by reference in their entireties.
In general, captions and subtitles in theatrical presentations have different meanings. For example, captions refer to commentary in the language of the primary audio, whereas subtitles are generally in a language other than of the primary audio. However, both are instances of text applied over the main image. Since embodiments of this invention apply equally to captions and subtitles, these terms are used interchangeable in this discussion.
Captions and subtitles are also frequently encountered as either ‘open’ or ‘closed’. Open captions or subtitles are visible to all viewers, and are ‘burned-in’, that is, made into an inextricable element of a main image, e.g., an image or content for presentation or display. Closed captions or subtitles, however, are not provided as a part of the main image. Instead, they are displayed by the action of the monitor or projector, or the set-top box or server driving the monitor, in conjunction with the display of the main image or content.
In some cases, e.g., in digital cinema presentations, the subtitles or captions are provided with metadata for their placement in the main image. In other cases, e.g., television, the closed captions are provided without placement information and the placement is left up to the presentation system.
Most television systems provide closed captions as a stream of text that is rendered by the display device. In digital cinema systems, captions or subtitles may be provided as timed-text, where text strings to be rendered in a default or explicitly specified and provided font, or they may be provided as still-frame images of the text.